Potencial de inóculo de fungos micorrízicos arbusculares em seis sistemas de uso do solo, na região nordeste do semi-árido do Brasil.

Abstract

The mycorrhizal associations are formed between symbiotic fungi and roots of the plant species. It is widely known that arbuscular mycorrhizal fungi (AMF) are important for the survival and development of plants. The roots carry an important role in the detention of nutrients of the substrate, avoiding loss of nutrients by leaching in this association, the fungi receive carbohydrates secreted by the roots of plants and absorb water and soil nutrients for plants. The objective was to evaluate the effects of the holding agroforestry about the potential infectivity of (AMF) in the areas of the Northeast in the semi-arid paraibano, by quantifying the number of spores, by counting direct, and the number of infective propagules of AMF in the soil, by the technique of (MPN), checking influence on the dynamics of seed AMF. Collections were made of soil in the dry season (august/2006) and the rainy season (february/2007) in six areas; five presenting environmental disturbances caused by the activity of human exploitation and presenting a preserved area of Caatinga, this being considered as controls. At each point of collecting soil was considered a radius of 2 m, where they were registered and identified the plant species tree / shrub and herbaceous occurring. The potential infectivity soil was defined from the most probable number method (MPN). The spores were removed from the soil of the areas of the points of collection by the method of wet screening, followed by centrifugation and flutter in 40% sucrose, this matter was centrifuged and placed in Petri dishes for the direct counting of spores. The data showed that the soils of the areas Pasture with Grass Buffel (PCB), Pasture with Forage Cactus (PPF), Fruits (F) Forestry with Eucalyptus (SE), Preserved Caatinga (CP) and Degraded Caatinga (CD), the farm NUPEÁRIDO showed infectivity and high density of propagules of arbuscular mycorrhizal fungi.